To meet demands for the applications in storage of consumer electronics—audio and video—a low-cost, hard disc drive is essential. The cost of currently available hard disc drives drastically exceeds the price level for audio and video applications needed to make those products affordable to consumer mass markets. Thus, it is desirable to reduce the cost of the components and labor required to fabricate a hard disc drive in order to reduce the overall cost.
Balanced by the demand for a low-cost motor for disc drives, there is an ever-increasing demand for disc drive performance. As the density of information stored on discs has increased, the size of the storage system has decreased. Correspondingly, greater precision and lower tolerance in the manufacturing is increasingly required for robust and reliable operation of disc drives. For example, to achieve increased storage densities, the read/write heads must be placed increasingly closer to the surface of the storage disc.
From the foregoing discussion, it can be seen that the bearing assembly which enables the storage disc to rotate is of critical importance. One bearing design is a fluid dynamic bearing. In a fluid dynamic bearing, a lubricating fluid such as oil, among other fluids, provides a bearing surface between a fixed member of the housing (i.e., the shaft) and a rotating member of the disc hub. Fluid dynamic bearings spread the bearing surface over a large surface area, as opposed to a ball bearing assembly, which comprises a series of point interfaces. This bearing surface distribution is desirable because the increased bearing surface reduces wobble or run-out between the rotating and fixed members. Further, the use of fluid in the interface area imparts damping effects to the bearing, which helps to reduce non-repeatable run-out. Thus, fluid dynamic bearings are an advantageous bearing system that enhances disc drive performance.
However, the greater precision and lower tolerance required for the fabrication of robust disc drives having fluid dynamic bearing motor presents a major obstacle in producing drives at a cost desirable for consumer mass markets. Therefore, there is a need for an improved fluid dynamic bearing motor having reduced fabrication costs without sacrificing drive performance by reducing stiffness or otherwise.